Transformer system



' p 1929. A. L. ATHERTON 1,729,091

TRANSFORMER SYSTEM Filed May 11, 1921 INVENTOR I WITNE SE I A/fm/LAf/zeror.

, ATTORNEY v Patented Sept. 24, 1929" UNITED STATES- PATENT OFFICE HOUSE'ELECTBIC & MANUFACTURING I VANIA.

Application filed na -11,:

My invention relates to motion picture machines and it has particular relation to the method of operating the lamps thereof, and

to the apparatus and the system of connections whereby suchlamps are supplied with electrical current. Q

This application is a continuation in part of my application, Serial No. 305,130, filed June 18, 1919, and assigned to the Westing- 1 house Electric & Manufacturing Company.

One object of my invention is to provide va method of operat' lamps of the above indicated character viiich will greatly increase the active life thereof.

A further object of my invention is to rovide a transformer connection particuarly adapted for use in connection with motion picture lamps operated in accordance with my improved method.

2 Briefly speaking, my invention comprises maintaining thefilaments of motion picture lamps heated during the periods of inactivity but to a lower degree of temperature than during the intermittent periods of service.

Heretofore, it has been customary in motion picture houses to provide to independent motion picture machines which are alternately employed in projecting the various pictures on the screen while at the same time the film in the other machine is being rewound. Thus, the lam of each machine is actively employed only lntermittently. Dur- 1 ing the periods intervening the active operation of each lamp, the lamp is permitted to '35 becomecooled'. Whenit is desired to again employ that machine for projection purposes, the full voltage for which the lamp is con-' structed is impressed thereon and the lamp filament is immediately raised to an incandes- 40 cent temperature. The wire which passes through the seal into the evacuated bulb is thus suddenly heated by means of a relatively high current. The glass which is sealed thereto is, however, cold and does not heat nor ex- 4 pand at the same rate as does the leading-inwire. Therefore, considerable stresses are set up which tend to crack the glass, thus destroying the seal.

According to my invention, the filaments 59 of the lamps are maintained heated but to a COIPANY, A CORPORATION OF PENNSYL- TRANSFORMER SYSTEM 1921. serial No. 488,712.

lower temperature during the inactive periods intervening between the active periods of service of the lamp, thus preventing the leading-in-wires and the immediately adjacent glass seal from becoming cooled. The filament 55. may be heated to such degree of temperature that when additional voltage is impressed thereon, in order to brighten the lamp for projection purposes, the difference between the rate'of expansion of the leading-in-wire 60 and of the immediately adjacent portions of the seal will be relatively slight, thus rendering the stresses set up therebetween negligible. Also, the filaments of lamps are injuredby sudden changes of widely varying tempzrature, so that heating the same somewhat fore applying full volta e thereto. serves to materially lengthen its ife. It may, of course, be permitted to cool directly after service, and to remain cool until a few minutes before it is needed for rojection purposes. Reduced potential may t ien be impressed on the lamp which may be focused while heating slowly.

- The accompanying drawin is a diagrammatic view illustrating one orm which my invention may assume. a

. In the drawing, I show a transformer comprising a primary coil 2 and a secondary coil 3, the latter of which is provided with taps 4 and 5 at, the respective ends thereof and an intermediate adjustable tap 6. A motion picture projection lamp 7 is connected to the tap 6 through a disconnecting switch 8 and to the tap 4 through a reversing switch;9. Likewise, a motion picture projection lamp 10 is connected to the tap 6 through a disconnecting switch 11 and to the tap 5 through the reversing switch 9.

It will be noted that the tap 6 is adjustable and that it is disposed closer to the tap 5 than to the tap 4. The purpose of such connection is that when the switches 8 and 11 are closed, one of the lamps will be provided with its normal operating potential, whereas, the other has impressed a reduced potential thereon. With the reversing switch 9 in the position indicated by the dotted lines, the lamp 10 will have its normal potential impressed thereon and the lamp 7 will have a 1 0 reduced potential impressed thereon, providing switches 11 and 8 are both closed. If theditions, one of the lamps will have impressed thereon its normal potential, while the other lamp will have impressed thereon a reduced potential. Upon the reversal of the switch 9 these conditions will be reversed and the lamp previously fully energized. will have impressed there-on a voltage below normal, thus maintaining it heated and illuminated sufficiently to permit focusingthereof but not enough to interfere with the picture being projected by the other machine.

I have found that under ordinary circumstances, with a full potential of 30 volts about 900 watts are consumed. \Vith the same machine the reduced potential may be 12 volts and the energy consumption 100 watts, which is suflicient to keep the lamp warm but is not suflicient to cause appreciable deterioration thereof. V

While I have shown but one form of my machine and have described in detail but a single application of the same, it will be apparent to those skilled in the art that various modifications and changes may be made therein without departing from the spirit and scope of my invention, as set forth in the appended claims.

I claim as my invention:

1. In combination with two motion icture projection lamps, a transformer win ing provided with taps whereby several currents of relatively difi'erent potentials may be derived from different sets of taps, one of said lamps being connected to one set of said taps whereby a predetermined potential is impressed thereon and the other lamp being connected to another set of said taps whereby v a relatively different potential is impressed thereon, and means for interchanging said connections.

2. In combination with two motion picture projection lamps, a transformer winding provided with a tap intermediate its terminals and disposed adjacent to one end, one of said lamps being connected to said tap and one terminal of the winding and the otherlamp being connected to said tap and the remaining terminal of said winding, and means for reversing said connection.

3. In combination with two motion picture projection lamps, a transformer winding provided with taps whereby several currents of relatively different potentials may be derived therefrom, one of said lamps being connected to one of said taps whereby a predetermined potential is impressed thereon and the other lamp bein connected to another set' of said taps where y a relativel different potential is impressed thereon, an switching means for reversing said connections.

4. In combination with two motion picture projection lamps, a transformer winding provided with ta s whereby several cur rents' of relatively different potentials may be derived therefrom, one of said lamps being connected to one of said taps whereby a predetermined potential is impressed thereon and the other lamp being connected to another set of said taps whereby a relatively difi'erent potential is impressed thereon, switching means for reversing said connections, and means for interrupting either of said currents independently of the other.

5. In combination with two motion picture projection lamps, a transformer winding provided with taps whereby several currents of relatively different potentials may be derived therefrom, one of said lamps being connectedto one of said taps whereby a predetermined potential is impressed thereon and the other lamp being connected to another set of said taps whereby a relatively different potential is impressed thereon, switching means adapted for interrupting both of said currents or either of said currents independently of the other.

In t stimony whereof, I have hereunto sub scribe my name this 26th day of April 1921. ALFRED L. ATHERTQN. 

